<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			var con = prompt();
			if(Boolean(con)){
				document.write("用户已经完成输入");
			}
			else{
				document.write("用户无输入");
			}
		</script>
	</head>
	<body>
	</body>
</html>
